Operation Panchai Palang (panther's claw) marks the start of what British commanders hope will be a decisive campaign against Taliban fighters in the populated and strategically important heartlands of Helmand province.

Gulab Mangal, governor of Helmand, has been pressing British and other foreign forces to seize and hold areas north of Lashkar Gah, the provincial capital, ahead of the Afghan presidential elections due to be held in August.

Taliban commanders have been threatening Afghans who intend to vote and polls suggest that concerns about security are the main reason why they would not vote.

"The message to Afghans is that the British forces are here and are here to stay," a British defence official said today. One of the immediate tasks is to surround and cut off Taliban forces around Babaji, bordering Helmand river, and Gereshk.

Some 500 British and Danish troops have been engaged in one of the biggest operations in southern Afghanistan, supported by American gunships and Canadian helicopters.

Ever since the British taskforce in Helmand was deployed three years ago, troops have captured towns from insurgents only to see them retaken soon after they left. The British did not have enough troops to hold land they had captured. UK commanders described the struggle against Taliban fighters as like squeezing a balloon: as soon as they bear down on one area, the insurgency pops up elsewhere, forcing them to redeploy, at which point the enemy reappears in the first place.

"We could not have done it before, we were too thinly spread," a defence source said, describing the current operation. He pointed to the deployment to Helmand of large numbers of US troops, the beginning of the planned deployment of more than 10,000.

Many of the US troops will be based in the southern part of Helmand, notably in Garmsir district. That will enable British troops based there, currently the Light Dragoons, to join the Black Watch and other units in Operation Panchai Palang, which is expected to continue for some weeks yet.